Method and apparatus for bi-directional communication between analog and digital devices

Abstract

A bi-directional communications interface includes a source multiplexer for connecting to a video source. The source multiplexer includes a source multiplexer input port for receiving an analog video signal from the video source, a source multiplexer output port for driving the video source with an upstream data signal, and a source multiplexer bi-directional port for coupling the analog video signal from the source multiplexer input port to the video cable and for coupling the upstream data signal from the video cable to the source multiplexer output port.

1. An apparatus comprising:
 a source multiplexer for connecting to a video source wherein the source multiplexer comprises:
 a source multiplexer input port for receiving an analog video signal from the video source; 
 a source multiplexer output port for driving the video source with an upstream data signal; and 
 a source multiplexer bi-directional port for coupling the analog video signal from the source multiplexer input port to a video cable and for coupling the upstream data signal from the video cable to the source multiplexer output port; 
 a lowpass filter for passing the analog video signal and blocking the upstream data signal at the source multiplexer input port; and 
 a bandpass filter for blocking the analog video signal and passing the upstream data signal at the source multiplexer output port; and 
 
 a sink multiplexer for connecting to a video sink wherein the sink multiplexer comprises:
 a sink multiplexer input port for receiving the upstream data signal from the video sink; 
 a sink multiplexer output port for driving the video sink with the analog video signal; and 
 a sink multiplexer bi-directional port for coupling the upstream data signal from the sink multiplexer input port to the video cable and for coupling the analog video signal from the video cable to the sink multiplexer output port. 
 
 
   
   
     2. The apparatus of  claim 1  wherein the source multiplexer comprises a diplexer. 
   
   
     3. The apparatus of  claim 1  wherein the analog video signal and the upstream data signal are frequency multiplexed in the video cable. 
   
   
     4. The apparatus of  claim 3  wherein the source multiplexer input port and the sink multiplexer output port each comprise a lowpass filter for passing the video signal and blocking the upstream data signal, and the source multiplexer output port and the sink multiplexer input port each comprise a bandpass filter for blocking the video signal and passing the upstream data signal. 
   
   
     5. The apparatus of  claim 3  wherein the source multiplexer and the sink multiplexer each comprise a diplexer. 
   
   
     6. The apparatus of  claim 1  wherein the analog video signal and the upstream data signal are time multiplexed in the video cable. 
   
   
     7. The apparatus of  claim 6  wherein the upstream data signal is transmitted through the video cable during a vertical blanking interval or a horizontal blanking interval of the analog video signal. 
   
   
     8. A method comprising steps of:
 receiving an analog video signal from a video source connected to a source multiplexer input port of a source multiplexer; 
 driving the video source by a source multiplexer output port of the source multiplexer with an upstream data signal from a video cable; 
 coupling the analog video signal from the source multiplexer input port to the video cable through a source multiplexer bi-directional port of the source multiplexer; and 
 coupling the upstream data signal from the video cable through the source multiplexer bi-directional port to the source multiplexer output port; 
 passing the analog video signal and blocking the upstream data signal at the source multiplexer input port by a lowpass filter; 
 blocking the analog video signal and passing the upstream data signal at the source multiplexer output port with a bandpass filter; 
 receiving the upstream data signal from a sink multiplexer input port of a sink multiplexer connected to a video sink; 
 driving the video sink at a sink multiplexer output port of the sink multiplexer with the analog video signal from the video cable; 
 coupling the upstream data signal from the sink multiplexer input port to the video cable through a sink multiplexer bi-directional port of the sink multiplexer; and 
 coupling the analog video signal from the video cable through the sink demultiplexer bi-directional port to the sink multiplexer output port. 
 
   
   
     9. The method of  claim 8  further comprising a step of frequency multiplexing the video signal and the upstream data signal in the video cable. 
   
   
     10. The method of  claim 9  further comprising a step of frequency multiplexing the analog video signal and the upstream data signal in the video cable. 
   
   
     11. The method of  claim 9  further comprising steps of:
 passing the video signal and blocking the upstream data signal at the source multiplexer input port and the sink multiplexer output port; and 
 blocking the video signal and passing the upstream data signal at the source multiplexer output port and the sink multiplexer input port. 
 
   
   
     12. The method of  claim 11  further comprising a step of time multiplexing the video signal and the upstream data signal in the video cable. 
   
   
     13. The method of  claim 12  further comprising a step of transmitting the upstream data signal through the video cable during a vertical blanking interval or a horizontal blanking interval of the analog video signal. 
   
   
     14. An apparatus comprising:
 a source multiplexer for connecting to a video source wherein the source multiplexer comprises:
 a first source multiplexer input port for receiving an analog video signal from the video source; 
 a second source multiplexer input port for receiving a downstream data signal from the video source; 
 a source multiplexer output port for driving the video source with an upstream data signal from a video cable; and 
 a source multiplexer bi-directional port for coupling the analog video signal from the first source multiplexer input port to the video cable, for coupling the downstream data signal from the second source multiplexer input port to the video cable, and for coupling the upstream data signal from the video cable to the source multiplexer output port; and 
 
 a sink multiplexer for connecting to a video sink wherein the sink multiplexer comprises:
 a sink multiplexer input port for receiving the upstream data signal from the video sink; 
 a first sink multiplexer output port for driving the video sink with the analog video signal; 
 a second sink multiplexer output port for driving the video sink with the downstream data signal; and 
 a sink multiplexer bi-directional port for coupling the upstream data signal from the sink multiplexer input port to the video cable, for coupling the analog video signal from the video cable to the first sink multiplexer output port, and for coupling the downstream data signal from the video cable to the second sink multiplexer output port; 
 
 wherein the analog video signal is frequency multiplexed in the video cable with the upstream data signal and the downstream data signal; and 
 wherein the first source multiplexer input port and the first sink multiplexer output port each comprise a lowpass filter for passing the video signal and blocking the upstream data signal and the downstream data signal, and wherein the first source multiplexer output port, the second source multiplexer input port, the sink multiplexer input port, and the second sink multiplexer output port each comprise a bandpass filter for blocking the video signal and passing the upstream data signal and the downstream data signal. 
 
   
   
     15. The apparatus of  claim 14  wherein the source multiplexer and the sink multiplexer each comprise a triplexer. 
   
   
     16. The apparatus of  claim 14  wherein the video source is a set top box and the video sink is a television monitor. 
   
   
     17. The apparatus of  claim 16  wherein the upstream data signal includes a user command received by the television monitor from a remote control. 
   
   
     18. The apparatus of  claim 17  wherein the downstream data signal includes on-screen display information for only one of the set top box and the television monitor in response to the user command. 
   
   
     19. A method comprising steps of:
 receiving an analog video signal from a video source connected to a first source multiplexer input port of a source multiplexer; 
 receiving a downstream data signal from a video source connected to a second source multiplexer input port of the source multiplexer; 
 driving the video source by a source multiplexer output port of the source multiplexer with an upstream data signal from a video cable; 
 coupling the analog video signal from the first source multiplexer input port to the video cable through a source multiplexer bi-directional port of the source multiplexer; 
 coupling the downstream data signal from the second source multiplexer input port to the video cable through the source multiplexer bi-directional port; 
 coupling the upstream data signal from the video cable through the source multiplexer bi-directional port to the source multiplexer output port; 
 receiving the upstream data signal from a sink multiplexer input port of a sink multiplexer connected to a video sink; 
 driving the video sink at a first sink multiplexer output port of the sink multiplexer with the analog video signal from the video cable; 
 driving the video sink at a second sink multiplexer output port of the sink multiplexer with the downstream data signal from the video cable; 
 coupling the upstream data signal from the sink multiplexer input port to the video cable through a sink multiplexer bi-directional port of the sink multiplexer; 
 coupling the analog video signal from the video cable through the sink demultiplexer bi-directional port to the first sink multiplexer output port; and 
 coupling the downstream data signal from the video cable through the sink demultiplexer bi-directional port to the second sink multiplexer output port; 
 passing the analog video signal and blocking the upstream data signal and the downstream data signal at the source multiplexer input port and the first sink multiplexer of the output port by a lowpass filter; 
 passing the upstream data signal and blocking the video signal and the downstream data signal at the source multiplexer output port and the sink multiplexer input port by a bandpass filter; and 
 passing the downstream data signal and blocking the video signal and the upstream data signal at the second source multiplexer input port and the second sink multiplexer output port by a bandpass filter. 
 
   
   
     20. The method of  claim 19  further comprising a step of frequency multiplexing the video signal in the video cable with the upstream data signal and the downstream data signal. 
   
   
     21. The method of  claim 19  wherein the video sink is a set top box and the video sink is a television monitor. 
   
   
     22. The method of  claim 21  further comprising a step of including a user command received by the television monitor from a remote control in the upstream data signal. 
   
   
     23. The method of  claim 22  further comprising a step of including on-screen display information in the downstream data signal for only one of the set top box and the television monitor in response to the user command. 
   
   
     24. The method of  claim 21  further comprising a step of pre-empting a previous on-screen display with a current on-screen display from a video source or a video sink in response to a remote command to avoid overlaying multiple on-screen displays on one another.